An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header, which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a housing, which may include adjustable concaves and performs a threshing operation on the crop material to remove the grain. Once the grain is threshed, it falls through perforations in the concaves onto a grain pan. From the grain pan, the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Material other than grain (MOG), such as straw, debris, dust, etc., from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the MOG and direct it out through the rear of the combine.
Generally, concaves may be adjustably mounted on one or both sides of the concave frame. Thereby, the distance, e.g. the clearance passageway for crop material to flow therein, between the concaves and the rotor may be adjusted. In order to adjust the clearance passageway, there exists various concave adjustment assemblies or mechanisms which allow concave adjustments to be made by the combine operator. Such adjust assemblies or mechanisms typically include a motor in driven relation to a gear train in connection with the concaves for moving the concaves radially inward or outward from the rotor.
However, some concave adjustment systems may lead to a decrease in the operational life of the threshing and separating system as well as to operator discomfort. Some concave adjustment systems are inflexibly mounted relative to the concaves and thereby may receive unwanted threshing forces, generated by the rotation of the rotor and/or resulting impar s on the concaves from the crop material during threshing, which can lead to damage of the concaves and breakage or failure of the concave adjustment system. For example, when a wad of crop material, especially damp crop material, enters the threshing chamber, the rotor may lag or become sluggish due to an inflexible and relatively unresponsive concave adjustment system that may not readily adjust the clearance passage between the rotor and the concaves. Additionally, for example, certain crop materials and field conditions, such as when harvesting a crop material in a field with green weeds, the rotor may tend to rumble, which can lead to damaging the threshing components as well as to operator discomfort during the time periods when the rotor is rumbling. Because some concave adjustment systems provide poor flexibility in the relationship between the rotor and the concaves, the excessive rumbling of the rotor is not alleviated. Further, with some concave adjustment systems which do not readily respond to impulsive force impacts, such as rocks contacting the concaves, impact damage on the raspbars, the mounts, or the rotor itself may still persist. In sum, some adjustably mounted concaves can lead to shortened operational life, costly repairs, and operator discomfort.
What is needed in the art is a cost-effective and responsive concave adjustment device.